Thermosetting epoxy resin compositions are widely used as adhesives and as materials to make molded articles. The aluminum chelate/silanol curing catalyst system is a type of catalyst system used to cure thermosetting epoxy resin compositions (Non-Patent Documents 1 and 2). Although generally known as a cationic epoxy-curing catalyst, this catalyst system in fact consists of a cationic active species and an anionic active species as depicted in the following formula.
[Non-Patent Document 1] Journal of the Chemical Society of Japan, 1993 (1), 1-14[Non-Patent Document 2] Journal of the Chemical Society of Japan, 1994 (7), 625-631